POSTSCRIPT TO VOLUME I 



This treatise on the FiHcales is divided into two parts. The object of 

 the first has been to recognise, to describe in detail, and to evaluate the several 

 criteria which are most suitable for use in the comparative treatment of the 

 Class : by comparison of the fossil remains to check the several features and 

 their details according to such evidence of their time of appearance as the 

 successive geological ages will afford : and so, partly by comparison of living 

 forms and partly by the more direct record of the Earth's crust, to arrive at 

 a sound basis for the phyletic grouping of the Class. 



This having been carried out in the above pages with such detail as the 

 limits of a single volume will allow, it remains to apply the method in re- 

 constructing the phylesis of the FiHcales from the ample, but nevertheless 

 fragmentary, facts available. This will be the subject of the Second Volume, 

 which will thus deal constructively with the material. The First Volume has 

 been analytical: the Second Volume will be mainly synthetic in its method. 



